Dental casting machine



May 15, 1928. 1,669,574

s. c, RIEKE DENTAL CASTING MACHINE Filed Aug. 26. 1925 S. C. R/EKE BY HIS ATTOR/YEVJ Patented May 15, 1928 T omen;

SIDNEY 0. man, or MINNEAPOLIS, mmnnsora.

DENTAL GASTIN G MACHINE.

Application filed August 26, 1925. Serial No. 52,629.

This invention relates to centrifugal casting'machines employing a carrier bar, having thereon a molten metal receptacle and a mold carried by said bar on the outer side of said receptacle. Such machines are wide-. ly used in the dental profession to cast inlays or bridge-work, and this invention relates especially to a centrifugal dental casts ing machine. I

t is the main object ofthe invention to provide a simple but efficient centrifugal casting machine having means for suddenly and sharply swinging the carrier bar and permitting the same to continue to swing after the momentum has been imparted. 111 a casting machine of this type, not only must the carrier bar he suddenly swung to pack the gold or other metal in the mold, but the bar must continue to swing fora suflicient length of time to permit the metal packed in the mold to cool and harden. This invention fills both requisites.

It is a further object of the invention to provide a casting machine wherein energy, preferably in the form of a compressed gas, may be stored and suddenly released to spin the carrier bar, imparting a sharp initial movement to the same and breaking its driving engagement therewith to permit the spinning of said bar to continue for sufficient time to cool the metal packed by centrifugal force in the mold.

It is a more specific object of the invention to provide in such a device, a piston rod carrying a rack adapted to engage a inion on the driving shaft, and tosudden y actuate said rod through a short stroke, means being provided for breaking the driving engagement when the rod is moved a predetermined distance.

A still further object of the invention is to provide means for re-settin the device after a casting has been formed or de ressing the piston rod whereby a considera 1e amount of gas will be compressed and stored for future use to actuate said rod and again operate the device.

These and other objects of the invention will be apparent from the following description made in connection with the accompanying drawings, whereinlike characters refer to similar parts throughout the several views, and in which:

Fig. 1 is a view partly in side elevation and partly in vertical section of the preferred form of the device; an

Fig. 2 is a fragmentary plan view show- 9 ing the driving engagement between the piston and the driving shaft.

In the preferred form of the-invention i1- lustrated, a square box-like casing or reservoir 3 is provided, having a relatlvely wide base flange 3", adapted to be secured to a support-ing surface. A ball valve 4 permits gas or air to be forced inreservoir 3 by means of a pump or other suitable device. The casing 3 carries, at its top portion, the cylinder 5 in communication with one side of the top portion thereof. Port 3" connects cylinder 5 with reservoir 3. A casing 6 of substantially rectangular shape, having the down-turned flange 6 and having a relatively small .cylindrical portion 6 adapted to lit over cylinder5, is secured to the top of reservoir 3 by means of a plurality of bolts 7.

In the flange 6 of easing 6, opposite the "cylinder 5, a plurality of ports 6 are formed,

the purpose of whichwill later be explained. The top wall of reservoir 3 is recessed somewhat at approximately its center portion to provide a seat for ball bearings-8 and likewise a seat is formed in the boss portion of casing 6 for similar ball bearings 8. The driving shaft 9 is vertically mounted for rotary motion in bearings 8, having its outer end projected somewhat above the boss of casing 6. The carrier bar 10, of standard construction, is rigidly secured to the outer end of shaft 9, carrying at one end the movable crucible or molten metal receptacle 11, on the outer side of which the mold 12 is socured, and, at the other end, the usual counter-weight 13, adapted to be adjusted and rigidly secured to bar 10 by means of the set screw 13. For rotating shaft 9, a piston 14. is provided in cylinder 5, piston rod 15 being preferably of "rectangular cross section and carrying a 'rack15 on its side ad'- jacentshaftft). Rack 15 is adapted to engage with the pinion 16, rigidly secured to the shaft 9. In the under side of piston rod 15, a pair of notches 17 are provided, one adjacent the outer end ijiereof which projects slightly beyond casmg 6' when the piston is in depressed working position, and the other of-which is spaced. the distance of end thereof, whereby the piston stroke from the outer notch. A spring pressed stud 18 is carried by the easing 6, adapted to engage notches 17, and the operating handle 18 is secured to the lower the stud engagement may be released suddenly when it to operate the machine.

The inner notch 17 is obviously engaged by stud 18 when the rack has been moved through its full stroke, thereby preventing the piston from crashing the pinion 16. The second stop means is provided in the form of a'split member 20 rigidly carried by rod 15 adapted to abut the side of easing 6- when the piston has moved through its full stroke. To permit the shaft to continue to rotate and spin arm 10, after the stroke has been given to the rod 15,'a cut-out or concave portion 15 is provided in said rod adjacent the inner end thereof, whereby the engagement between pinion 6 and rack 15* will be broken when the end of the stroke is reached. A pressure gauge 19 is illustrated on one side of casing 3 conveniently located for observation while the reservoir is being filled with a pump or compressed gas container. vIn operation, rod 15 is first depressed until the outer notch 17 is engaged,by the stud 18, releasably locking the rack 15. I is then pumped into reservoir 3 through the valve 4. 'An ordinary pump-may be used with a connection fitting the entrance to said valve or a compressed gas tube or tank may seconds,

the metal be connected to said valve by means of a suitable conduit and connection member. The mold 12, of course, is made and molten metal put in the crucible 11. The handle 18 is then pressed down and promptly recompressed gas will act against piston 14, sharply forcing the same outwardly and. imparting a sudden twist or rotation to the shaft 9. Arm 10 will be given a sharp initial impulse and at the end of the stroke of piston 14, will be permitted to continue to rotate. In the type ofmae chine illustrated, using the ball bearings, this rotation will last for a period of about thirty which will be amply sufficient for forced into the mold 12 to cool. The sharp start given the bar 10 will thoroughly pack the metal into the mold. The ports 6 at one side of'casing 6, of course, permit ready displacement of the air in cylinder 5 and easing 6, so that therewill be no considerable amount of back pressure.

When it is desired to again use the device,

' the piston 14 will be depressed by ressing the end of rod 15 inwardly, there y comressing a considerable amount of air or gas in the reservoir 3, so that, at most, it will be necessary to only pump a small amount of additional air or gas into the reservoir to obtain the desired pressure for operating the device. From the above description, it will be seen is desired Air or gas.

xtherewith when said bar is swung,

few parts and can be manufactured at a reasonable expense.

It will, of course, be understood that various changes may be made in the form, details, proportions and arrangement of parts without departing from the scope of the invention, and hat, if desired, other means ma be employed to suddenly project the rats 15".

What is claimed is:

1. A centrifugal casting machine havin in combination a rotatable carrier, a mol adjacent one end of said carrier, a 'receptacle for molten metal communicating with said mold and disposed inwardly thereof, means for rotating the said carrier and means for suddenly releasing gaseous pressure against said first mentioned means to suddenly rotate said carrier.

2. A. centrifugal casting machine having in combination a rotatable shaft, a carrier bar rigidly secured transversely of said shaft, a molten metal receptacle adjacent one end of said bar, a mold on the outer side of said receptacle adapted to communicate a cylinder adjacent said shaft, a piston working in said cylinder, a piston rod having driving connection with said shaft, and means for suddenly subjecting said piston to a considerable pressure to rotate said shaft and swing said bar.

3. A centrifugal castin machine having in combination a rotatab e shaft, a carrier bar rigidly secured transversely of said shaft, a molten metal receptacle adjacent one end of said bar, a mold on the outer side of said' receptacle adapted to communicate therewith when said bar is swung, a reservoir for containing gas under pressure, a cylinder communicatlng with said reservoir, a

iston movablein said cylinder, a piston rod liaving driving engagement with said shaft, and means for suddenl subjecting said piston to .the pressure of the gas within said reservoir to suddenly rotate said arm.

4. The structure set forth in claim 3, said shaft having a drivin pinion secured there- 'to, a rack on one si e of said piston rod adapted to engage said pinion, and means for breaking the driving engagement be-' tween said parts when said through a predetermined 'stance, to permit said shaft to continue to rotate.

5. A centrifugal castin machine having in combination a rotatab e shaft, 9. carrier bar rigidly secured thereto, a mold adjacent one end of said carrier bar,

receptacle disposed inwardly of said mold a molten metal' iston has moved and communicating at one end therewith, a cylinder adjacent said shaft, a piston working in said cylinder through a predetermined stroke, a piston rod having driving connection with said shaft, means for suddenly moving said piston to rotate said shaft, said piston rod having a recessed portion therein to automatically cause disengagement between said driving connection and said shaft when said piston has reached the end of its stroke. I

In testimony whereof I aflix my signature.

SIDNEY C. RIEKE. 

